Not Applicable
Not Applicable.
The invention concerns a machine tool, and in particular, a machine tool for cutting treatment of workpieces, comprising a machine frame, a workpiece table mounted on the machine frame, and an approximately horizontally disposed processing unit which is mounted to the machine frame.
In known circular table machine tools, several processing units having horizontal work spindles (Z-direction) for processing a workpiece provided on the circular table, are arranged about the rotatably disposed circular table. The processing units are mounted on the side of the base of the circular table, respectively. In machine tools of transfer lines, the processing units are also mounted to the side of the base of the machine tool.
In certain applications, e.g. high-speed or high-precision treatment or heavy cutting, displacement, in particular in the Z-direction, can occur due to high acceleration and processing forces between the workpiece and the tool, such that the desired precision cannot be achieved. Such forces occur in particular if the workpiece and processing unit are movable relative to one another in this direction.
It is therefore an object of the present invention to effectively prevent such displacements between the workpiece side and the tool side in machine tools of the above-mentioned type.
This object is achieved in accordance with the invention in a surprisingly simple manner in that the processing unit is mounted also to an upper support of the machine frame which overlaps the workpiece table.
While with the hitherto known machine tools, the horizontal processing unit is mounted only at the bottom of the machine frame, in accordance with the invention the processing unit also is mounted via the upper support at the top of the machine frame. This upper mounting prevents displacement of the processing unitxe2x80x94which was hitherto possiblexe2x80x94relative to the workpiece due to the forces acting thereon during processing, in particular in the Z-direction. These forces are accommodated in accordance with the invention only by the machine frame which is self-contained through this upper support. This frame can be produced as a one-piece casting or be composed of several interconnected, in particular welded, individual parts. The inventive machine tool can have one or more spindles.
In preferred embodiments of the invention, the upper support overlaps the workpiece table and extends from a side of the frame opposite to the processing unit. It is also possible that the support overlaps the workpiece table or the processing unit from another side.
In a further advantageous embodiment, the processing unit is displaceably guided on the machine frame in at least one guide which is mounted to the upper support. A slide of a slide unit can e.g. be guided in this at least one guide by means of which slide unit a work spindle is displaced in the X, Y and Z direction.
The at least one guide extends preferably approximately horizontally on the upper support to guide an X slide of the processing unit. This horizontal guide mounted to the upper support forms the upper mounting of the processing unit on the machine frame.
In one embodiment of the invention, the upper support is supported on the machine frame on the side of the processing unit. For this purpose, e.g. at least one, and preferably two, vertical supports, provided on the side of a processing window of the processing unit, can be provided on the machine frame. The at least one approximately vertical guide can be provided on the vertical support to guide a Y slide of the processing unit. This vertical guide forms the upper mounting of the processing unit on the machine frame.
In another embodiment of the machine tool, the workpiece table is disposed to be rotatable about a central support of the machine frame extending upwards and beyond the workpiece table, wherein the upper support is mounted to said central support to radially overlap the workpiece table. In such a circular table machine tool, the forces acting on top onto the processing unit, in particular in the Z-direction, are transferred via the overlapping upper support and the central support to the machine frame.
In a further development of this circular table machine tool, the workpiece table is mounted to the central support via a pivot bearing provided below and above the workpiece to be treated. Through guiding of the forces acting on the workpiece or the workpiece table into the central support above and below the processing plane, the forces acting on the circular table above its lower pivot bearing are accommodated by the machine frame.
In another further development of the circular table machine tool, several upper supports, each overlapping the workpiece table and offset in the circumferential direction of the central support, are disposed for several processing units on the projecting central support. The upper supports can be combined to form one single upper support having several arms.
In other embodiments of the inventive machine tool, opposing sides of the upper support are provided with one processing unit each. In such a machine tool, which can be used in particular as a machine tool of a transfer line, the forces acting from above onto the two processing units in the Z-direction, are transferred to the machine frame via the same overlapping upper support.
Further advantages of the invention will be apparent to those skilled in the art from the description and the drawings. The features mentioned above and below in accordance with the invention can be used individually or collectively in any arbitrary combination. The embodiments shown and described are not to be understood as an exhaustive enumeration but rather in an exemplary character for describing the invention. The invention is schematically shown in the figures to emphasize the essential features of the invention. The illustrations are not necessarily to scale.